2012 Dragonfly Swarm Project Year-End Report: Conclusions

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It’s time for part 3 of the yearly Dragonfly Swarm Project report! Today, I present the results of the predictions I made last year based on the data you all have contributed over the last 3 years, plus I’m proposing a challenge to you. Last year I made three predictions, so I’ll address those first, but then I want to get some feedback from YOU and see what you think. Ready? Let’s go!

This year was an interesting year in many ways, so the conclusions I thought were going to be so clear-cut and consistent from year to year aren’t necessarily as predictable as expected. That makes for exciting science though! The first prediction was the most straightforward:

Old Prediction: Dragonfly swarming will be most commonly reported east of the Missouri River in the U.S.

This is the one constant in this project each year. The space between the Missouri River and the Mississippi River typically produces several swarms each year, but I think it’s safe to make a new prediction based on the data gathered so far:

New Prediction: US dragonfly swarms are most common east of the Mississippi River.

As I stated last year, I think a lot of this has to do with the amount of water in the eastern US relative to the west. There is more habitat available to dragonflies in the east and likely more dragonfly individuals present in the wetter areas than in the arid west (though I don’t have data to back this up – will be looking through the literature for evidence). To have swarms, you need a lot of dragonflies in one area. You see dragonfly swarms in the west, but there are often identifiable special conditions that concentrate the dragonflies within an area at the time of the swarm. I have a few ideas about that that I’ll get to…

Old Prediction: Most swarms reported will follow flooding or heavy rains.

This prediction was… partially correct. While there were still reports of flooding or heavy rains in 263 of the 705 swarm reports made in 2012, you’ll notice that that’s not even half the reports. In fact, 314 reports indicated that there was no flooding or heavy rains in the area prior to swarming events, which suggests that rains might not play as strong a role in swarm formation as I previously thought. That said, I still think that flooding is an important factor and if you compare the areas of the country where flooding took place in 2012 and the location of swarms, there appears to be a nice correlation between the two. Sadly, I don’t possess the technical expertise to actually show that to you at this time, so you’ll just have to take my word for it. Based on the 2012 data, I have developed a new idea about possible factors in swarm formation, which I’ll discuss later. And I make this prediction:

New Prediction: 40% or more swarms will be observed after flooding or heavy rains in 2013.

I still think heavy rains and floods are a major factor in swarm formation, so I suspect that I will continue to get a lot of swarms reported that occurred with major rains/floods.

Old Prediction: There will be more dragonfly swarms reported from the northern Midwest (Minnesota, Michigan, Wisconsin, Illinois, Iowa, etc) in 2012 than in 2011. Similarly, there will be very few reports of swarms from eastern Ohio, Pennsylvania, Virginia, and West Virginia.

This prediction was based on an idea I had after two years worth of data collection: that areas where there were big weather events and massive dragonfly swarming in one year would not have many reports the following year when that massive swarming was due to flooding.  My idea was that flooding in an area might deplete the nymphal population that would emerge the following year. I made the prediction based on a comparison from two seasons and wasn’t sure it was going to hold true in 2012. However, I crunched a few numbers and made a few maps, and here’s what I discovered. In 2010, there was heavy activity in the north central US, with reports from Iowa, Minnesota, Michigan, Illinois, and Wisconsin making up 36.8% of the total reports for the year. Iowa and Illinois alone made up over 20% of the reports. In 2011, however, those five states made up only 7.8% of the reports. Things picked up in 2012 such that 18.9% of observations were made in the north central US. So, that part of the prediction was correct: swarming activity dipped strongly the year after the flooding in these states and then increased the following year. So far so good! But what about that second prediction? I have numbers if you are interested in them, but the map will show it so much more clearly. In 2011, a massive number of reports were made in Ohio, Pennsylvania, Virginia, and West Virginia, close to half of the reports. The map of the 2011 data in that area looked like this (click images to make them larger), and focus on the four states of interest, that big blotch of nearly solid green on the upper mid-Atlantic states:

2011 Static NE

Clearly, there was a major event happening in OH-PA-WV-VA, and indeed there was a lot of rain and flooding in that area that resulted from Hurricane Irene and Tropical Storm Lee. Lots of flooding meant lots of swarms in 2011. This is that same area in 2012:

2012 Static NE

Now THAT is a huge difference! Clearly there were far more swarms taking place in this region in 2011 than in 2012, so the second part of the prediction held true as well. The sample size is small and it’s hard to make broad conclusions without at least a few more year’s worth of data, but I think the data so far suggest that heavy swarming in a location one year results in low swarming the following year.

That said, there was no obvious and large center of activity this year. In fact, there were only two areas where large swarming events occurred: the New Jersey/southeastern New York area and Colorado. Comparing the 2012 data to 2013 data for Colorado isn’t fair because Colorado is a western state that doesn’t normally have a lot of swarming activity. So, I am going to make this prediction for 2013:

New Prediction: There will be fewer swarms in the New Jersey area in 2013 than in 2012.

Ultimately, however, the event in New Jersey wasn’t one the mega events you all have documented in the last few years, so it might not show the same sort of pronounced dip in activity highlighted in the maps above. Plus, the data from New Jersey is confounded because the eastern migration passes through the state in the fall.  We’ll just have to wait and see what happens!

I have a few ideas about why dragonfly swarms form and why they are important, but in the interest of keeping this post a reasonable length I am going to save them for another post. However, I promised you a challenge, and here it is: what do YOU think? I want to see if you all can come up with exciting, new ideas that I haven’t considered by answering two questions:

1. Why do static dragonfly swarms form? Feel free to list multiple suggestions for why they form at all, in addition to why they form in the locations where they have been observed. And…

2. What roles do you think static dragonfly swarms play in the environment? I.e., why are dragonfly swarms important?

I have my own ideas for about this behavior, but sometimes it’s good to get some fresh perspective.  That’s where you all come in! Feel free to base your answers on your own observations, the information I have shared on my blog, or any other source.  And just to keep things interesting, I’m offering a small dragonfly themed prize pack for a few of my favorite responses. If you want a chance at winning, offer some answers to the questions before 10AM EST Sunday, February 10, when I’ll post the reasons I propose for why these swarms form and why they’re important. I look forward to hearing your ideas!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

2012 Dragonfly Swarm Project Year-End Report: Distribution of Swarms

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It was another great year of data collection for the Dragonfly Swarm Project!  I continue to be impressed by the number of people who participate in this project, especially as it’s hard to promote it  in the hopes that someone might see a swarm and most people actually find the project after they’ve already seen a dragonfly swarm.  Still, over 700 reports were made in 2012 and that’s pretty darned good!  So, what does that data tell us?  The next two posts will focus on what we can learn from the data so far.  Today, I present the long-awaited maps (I think this year’s maps took a year or two off my life with all the stress they caused…) and next week I’ll discuss some of the patterns that I’m seeing in the data after three seasons of data collection.  Let’s dive into that data!

Like last year, I’ve split the map data into two videos.  It’s easiest to see changes over time when the images I create are presented as a series, so each map you’ll see in these videos represents the swarms that occurred during the time frame indicated at the top of the screen.  The pushpin colors mean something too: red represents a static swarm and blue represents a migratory swarm.  My apologies that the blue pins are a little hard to see on the map – they show up easily in Google Earth, but not so well in the images it produces.  For the best viewing experience, try watching the videos in full screen mode by clicking on the icon with the four arrows in the bottom right corner of the video player.  You’ll be able to see the changes from week to week more easily that way.

The first set of maps document the cumulative data for the year and show the overall pattern of swarm locations in 2012.  Each week’s new sightings are added to the previous weeks’:

The second set of maps shows the data for each month individually and by swarm type.  The first set of maps are the static swarms and the second are the migratory.  Each map represents only the data for the month indicated at the top of the video rather than showing the cumulative data.  For the migratory swarms, look closely along the southeastern and east coasts.  The pushpins are hard to see against the blue water of the ocean:

As you can see, there were once again more swarms reported east of the Missouri River than west of it.  In spite of the fact that Colorado made it into the 5 states with the most reports in 2012, there just aren’t that many dragonfly swarms in the west and some states (Montana, Wyoming, New Mexico) were entirely unrepresented this year.   Dragonfly swarms definitely appear to be more common in the east than the west.

In 2010, the center of activity was the western Great Lakes states and Iowa and last year it was the Pennsylvania/Ohio area.  This year, the activity was heaviest in the New Jersey area and northern New England coast in the mid to late summer and around the Chicago area in the late summer.   Each year seems to have a different center of activity, and I have a hypothesis for why this happens.  I’ll get to that in the next year-end report!

This year was an odd migration year.  The migration down the east coast has been documented several times in various publications, so it’s a fairly well-established route.  This year, there were very few reports of migratory movements in the east during the typical migration season in late August and September.  In fact, there were hardly any!  While most of the migratory movements reported this year did occur in the usual place, within a few miles of the coastline, the timing was all wrong: most were observed in June and July, much too early for the usual migration.  Again, I have a hypothesis that might explain this, but you’ll have to wait until next time.

The migration along the west coast was also quite weak this year.  That migration has a known set of conditions associated with it, a particular wind direction and a specific temperature.  The dragonfly people in Washington and Oregon were going out this year to the places they usually see migrating variegated meadowhawks on fall days with the right conditions and… nothing!  People were looking, and looking hard, so it seems that it was just a weak year for the migration overall, on both coasts.  I don’t even know how to explain the western migration fail though.  That’s just weird as that one is SO specific and occurs every year almost like clockwork!

Finally, I can say with more certainty that dragonfly swarms really aren’t a rare phenomenon and they happen more often than I’d ever expected when I started this project.  That is in keeping with the last two season’s worth of data.  However, last year I was uncertain whether I would continue to see an increase in the number of swarms reported every year and that has not been the case.  In 2010, I got about 650 reports.  Last year I got over 1100!  This year, I’m back down to 700.  I have a feeling that 600-800 swarm reports per year is normal and that the several hundred reports I got over a 3 week period last year were related to a set of perfect conditions that allowed a massive boom in dragonfly activity right toward the end of the year rather than an increase in participation in the project.  I’ll explain why I think that boom happened in the next part of the year-end report, but I predict that next year we’ll see the same sort of numbers we did this year, barring any sort of odd convergence of conditions that allow another 2011-style reporting boom.

If you’d like to see images of the maps of all the data for the year, I’ve uploaded them to my Yearly Maps page.  There, you can view the maps for static, migratory, and all swarms by year, which should make comparing between years fairly easy.  Click on the images to see a larger version of the map – they’re very tiny on the yearly maps page.

That’s it for this installment, but part three of the year-end report (the conclusions) will be up on Sunday.  It should be pretty interesting!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

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Have you seen a dragonfly swarm? I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes! Thanks!

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Want more information? Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!

Swarm Sunday – I’m Calling It

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The weather’s been doing strange things recently and I’ve only seen two total dragonflies in the past several weeks, so I’m declaring the dragonfly swarm season officially over.  This means that it’s time to start wrapping up by posting some year-end reports this season’s data.  Look for those to start in a couple of weeks.  In the meantime, it occurs to me that I received two reports a couple of weeks ago, right as Hurricane Sandy was barreling toward the east coast, that I forgot to post.  They were reported in these locations:

USA:

Miami Beach, FL
Deer Park, TX

And with that, the American dragonfly swarm season ended!

On a somewhat related front, the Migratory Dragonfly Partnership (MDP) has changed their data submission website a bit.  They are now accepting both dragonfly pond watch data AND migratory dragonfly sightings.  If you’ve submitted migratory sightings to me, no need to submit again – I’ll be sharing all of my migration data with the MDP team anyway.  However, if you haven’t gotten involved in the Dragonfly Pond Watch, however, I encourage you to do so!  All you need to do is make observations of a few easily recognizable species at a nearby pond once a month.  If you’re already out walking your dog or photographing things, why not collect a little data while you’re at it?  The MDP is a really great group of dragonfly researchers and they would love to have your data!

Happy Sunday everyone, and look for the first year-end report in a few weeks!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

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Have you seen a dragonfly swarm? I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes! Thanks!

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Want more information? Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!

Swarm Sunday (on Monday) – 9/30/2012 – 10/6/2012

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It was yet another slow week, with swarms reported from only the following locations:

USA:

Fairhope, AL
Noank, CT
Pensacola Beach, FL
Cherry Hill, NJ
South River, NJ
Woodbridge, NJ
Scarsdale, NY
Yonkers, NY
Alexandria, VA

You’ll notice most of these swarms occurred in the northeast with only a few in the south.  They were nearly all static swarms too, so the dragonflies seem to be staying put for now.  Maybe we’ll see more migratory movement next week?

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

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Have you seen a dragonfly swarm? I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes! Thanks!

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Want more information? Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!

Swarm Sunday – 9/23/2012 – 9/29/2012

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The swarming activity picked up a little this week, though perhaps not quite as much as I’d hoped.  Swarms occurred in the following locations:

USA:

Mystic, CT
Apopka, FL
Cape San Blas, FL
Destin, FL
Gulf Breeze, FL
Santa Rosa Beach, FL
McLeansboro, IL
Hoboken, NJ
Lawrenceville, NJ
North Arlington, NJ
Hastings-On-Hudson, NY
Lumberton, NC
Ocean Isle Beach, NC
Raleigh, NC (3 reports)
Cedar Park, TX
Kyle, TX
Kenosha, WI

There’s a strange distribution of swarms this week.  About half of them are in the northeast (New York and New Jersey) and the other half are in the southeast (North Carolina and Florida).  It’s a little odd that there’s nothing in between, but at this point I’m giving up trying to explain what’s going on until the season’s completely over.  Maybe I’ll have a better idea of why the end of the season is so strange if I can look at the whole season.  Or maybe not!  Guess we’ll have to see.

While there seems to be little activity happening in most of the rest of the country, the field station where I work, Prairie Ridge, has been quite the hotbed of dragonfly activity!  Between my coworkers and me, we’ve seen 7 swarms on the grounds over the past two weeks.  The last few days have been especially exciting.  Right around 4:30 or 5pm everyday, we’ve been seeing groups of dragonflies flying over the prairie.  They’re green darners mostly, though tonight there were some black saddlebags mixed in too.  The dragonflies fly from about 4 feet to 20 feet in the air, swooping back and forth over the grass.  I get a thrill from each and every swarm I see, but these swarms have been especially thrilling: immediately above the area where the dragonflies have been flying are chimney swifts, 100 or more.  Many people have told me about swallows flying above the dragonfly swarms they’ve seen – it happens often.  However, chimney swifts are not commonly reported.  It is really something to look out toward the sun in the distance and see big swarms of both dragonflies and chimney swifts!  I hope they’re eating all the mosquitoes that keep biting me.  :)

Please keep reporting swarms if you see them.  The season normally ends in a couple of weeks, so it will be interesting to see how this very strange season plays out!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

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Have you seen a dragonfly swarm? I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes! Thanks!

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Want more information? Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!

Swarm Sunday (on Monday) – 9/16/2012 – 9/22/2012

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Another very slow week!  Swarms occurred in the following locations:

USA:

Lilburn, GA
Boody, IL
Quincy, MA
Clarksboro, NJ
Raleigh, NC
Ovilla, TX

Six swarms last week.  Six!  Note to dragonflies: do you call that a migration?  Huh?  Pathetic…

This is getting weird.  Allow me to place this week’s swarm data into perspective.  During the same 7 day period last year, I got 147 reports.  The year before I got a third of that, but it was a much slower year and Hurricane Irene was’t wreaking havoc on the behavior or the American dragonfly population.  I got many reports each week into mid-October.  This year, I got 6 reports and it’s only September.  Based on my last two years of data collection, I would expect many, many more reports than this, maybe 10 times what I got last week.  Instead, I got 6.  This should be the peak migratory season, and hardly anyone is seeing anything out there!

I had been debating publishing my findings for this project after only three years of data collection, ]i.e. at the end of this season, rather than waiting the full five I had been planning for.  I thought I had this behavior under control and knew what to expect.  However, this year’s migration is reminding me of something that’s important to consider when you’re dealing with biological phenomena, particularly those that are dependent on weather: no matter how well you think you understand a system, nature has a way of throwing wrenches into your data collection.  She’s throwing a big wrench in the works this year!

I’m still hoping there will be one more surge in activity, a clear indication of the migration in the eastern US, before mid-October when the season usually ends.  It’s going to be interesting to see what happens in the next few weeks!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

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Have you seen a dragonfly swarm? I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes! Thanks!

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Want more information? Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!

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Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com

Swarm Sunday – 9/9/2012 – 9/15/2012

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It was a shockingly slow dragonfly swarm week this week!  Swarms occurred in the following locations:

USA:

Happy Camp, CA
Omo Ranch, CA
Waterford, CT
Gainesville, FL
Redington Beach, FL
Edwardsville, IL
Hume, IL
Coralcille, IA
Dubuque, IA
Iowa City, IA
Mashpee, MA
International Falls, MN
Reno, NV
Flanders, NJ
East Hampton, NY
Holden Beach, NC
Hebo, OR
Montgomery, PA
Ocean Park, WA
Sun Prairie, WI (2 reports)

Canada:

Mississauga, ON

How strange that there have been so few swarms this week!  I’ve heard reports from several people along the east coast of weather that changed from very warm to cool literally overnight, just like what happened where I live.  Last Saturday we had a huge storm and Sunday was a good 20 degrees cooler.  Perhaps the cold front is impacting the dragonfly flight?  I really have no idea what’s going on at this point.  It’s very odd to have so few swarms in the middle of the normal peak season.

About half of the swarms reported this week were migratory swarms, however.  The migration seems to be ongoing in the Midwest and along the west coast as most of the swarms reported from both regions were migratory.  But in the east…  Still nothing!  There were two reports in the same area of Florida of a massive migratory swarm, but where did it come from?  No one reported any movement in the east all week and then a giant swarm appeared out of nowhere in Florida.  Curiouser and curiouser!  Normally I get 20 reports of a single big swarm moving down the coast in 4 or 5 different states, but no one saw this one before it hit Florida.  Did it originate in Florida?  Or did all those people simply miss this one?

Honestly, though, getting unexpected results can be more exciting than confirming what you already know.  Now I’ve got this big mystery, an odd thing that I can’t explain.  Perhaps this coming week will provide some answers, so keep those reports coming!

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Unless otherwise stated, all text, images, and video are copyright © C. L. Goforth

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Have you seen a dragonfly swarm? I am tracking swarms so I can learn more about this interesting behavior.  If you see one, I’d love to hear from you!  Please visit my Report a Dragonfly Swarm page to fill out the official report form.  It only takes a few minutes! Thanks!

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Want more information? Visit my dragonfly swarm information page for my entire collection of posts about dragonfly swarms!

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Unless otherwise stated, all text, images, and video are copyright © TheDragonflyWoman.com